Johnson will need to be in a cast for six weeks while his thumb heals, but he's expected to be back in action by training camp, the team announced.
Johnson, 25, was a solid two-way option for the Heat in the 2017-18 season. He averaged 11.7 points, 3.4 rebounds and 2.3 assists while shooting 43.5 percent from the field and 36.7 percent from three in 28.5 minutes per game across 72 games (39 starts).
He was quieter in five postseason games against the Philadelphia 76ers, however, as he averaged only 8.0 points and 1.6 rebounds in just 16.2 minutes per game. Part of that was related to his thumb injury, which he suffered in Game 3.
Johnson projects to be a big part of Miami's future. He'll make $19.2 million in the 2018-19 season, although that salary—along with the $90.2 million due to Hassan Whiteside, Goran Dragic, James Johnson, Kelly Olynyk, Dion Waiters and Josh Richardson next season—doesn't leave the Heat with any wiggle room come free agency.
And with no draft picks for June's draft currently, the Heat will need to rely on trades this offseason to tweak their roster in meaningful ways.